Unusual Magnetic and Transport Properties of Layered Intermetallic Compounds Gd_1-xLa_xMn₂Ge₂ (I)
Reentrant Ferrimagnetism in the System Gd_1-xLa_xMn₂Ge₂

Abstract

In this paper, we report experimental results on the overall magnetic properties of intermetallic compounds Gd_1-xLa_xMn₂Ge₂ (0≤x≤1.0) with a ThCr₂Si₂-type layered structure. In GdMn₂Ge₂, a first order transition was observed from antiferromagnetic to ferrimagnetic state at T_t3 below T_N with decreasing temperature, while in Gd_1-xLa_xMn₂Ge₂ with x = 0.075 and 0.050, two kinds of first-order transitions, from ferrimagnetic to antiferromagnetic and from antiferromagnetic to reentrant ferrimagnetic states were observed at T_t2 and T_t3 after they become ferrimagnetic below T_t1. As x further increases canted ferrimagnetism appears with a compensation temperature in all the ordering temperature regions for 0.10 < x < 0.40, whereas no compensation behavior was observed for x > 0.50. The compensation behavior as a function of temperature is discussed on the basis of the two-sublattice molecular-field model.